Changes in Neuromuscular Function of the Quadrceps Muscle with Aging

The present study was designed to provide further insight into the neuromuscular mechanisms that determine the decrease in maximum strength and strength development of the quadriceps muscle with aging. Different neuromuscular tests were performed in order to assess the neural and muscular changes. The age-related decrease in isometric maximum voluntary torque (iMVT) was accompanied by a decline in voluntary activation and normalized surface electromyographic (EMG) amplitude. Mechanical parameters of explosive voluntary strength were reduced while the corresponding muscle activation remained primarily unchanged. The spinal excitability of the vastus medialis was not different while maximal M wave (Mmax) latency was longer. Contractile properties and lean mass were reduced. In conclusion, the age-related decline in iMVT of the quadriceps muscle might be due to a reduced neural drive and changes in skeletal muscle properties. The decrease in explosive voluntary strength seemed to be more affected by muscular than by neural changes.